the problem is that that technology has really widespread. it is also been talked about by domestic extremist groups. so although it is predominantly used by al qaeda associated overseas, we really can't draw that conclusion now. >> one of the most fascinating part of the story is usually when there is a big terrorism event, a group or people come forward and claim responsibility so the fact that there's been silence on this is a little bit perplexing. give us details on why they would or wouldn't do that? >> as a general matter, when al qaeda has been associated with an attack and it's an international terrorism group, that overseas group has taken credit. we haven't seen that. and my estimation is every day that passes that we don't see a claim from overseas, it makes it more and more likely that it's a domestic group. quite often domestic groups have not taken credit for it because taking credit for it would make them a much higher profile target for the fbi to go and find them. >> i want to get to the ricin story. do you -- it is strange